When a vaginally-delivered human infant is breast-fed he/she will have a gastrointestinal microbiome that is unique in composition and diversity compared to any other time in their life. The GI microbiome is dominated by a single organism which can be present at high concentrations (up to and over 70% of the total microbiome). However, the obstetric standard of care in a typical hospital today involves births from both Cesarean Section (C-section) and vaginal delivery, followed by human milk or infant formula feeding for the baby. The surgical suite and levels of cleanliness for the mother pre- and post-op in many modern hospital settings are such that in many cases the infant will not get seeded with bacteria normally found in the microbiome of the vagina or gastrointestinal tract of the mother, resulting in a dysbiosis in the baby whether delivered by C-Section or vaginal births or fed by mother's milk or infant formula. Furthermore, dysbiosis can also be caused by infants losing the beneficial Bifidobacterium as a result of illness or medical intervention (e.g., antibiotic treatment). The dysbiosis of the infant microbiome leads to increased gastrointestinal problems and delayed or altered immunological programming and tolerization. The consequences of early dysbiosis are considered to have an impact throughout the entire life of that individual.
Human milk contains a significant quantity of complex oligosaccharides (up to 15% of total dry mass) in a form that is not usable as an energy source for the baby nor for most of the microorganisms in the gut of that baby. Certain microorganisms such as Bifidobacterium longum subsp. infantis [B. infantis or BI] have the unique capability to consume the specific complex oligosaccharides such as those found in human or bovine milk (U.S. Pat. No. 8,198,872 and U.S. Pub. No. 2013/0195803, the contents of which are incorporated herein by reference). When B. infantis comes in contact with certain complex oligosaccharides a number of genes are specifically induced within the bacterium whose protein products as enzymes and binding proteins are responsible for the uptake and internal deconstruction of those complex oligosaccharides, and the individual sugar components are then catabolized to provide energy for the growth and reproduction of that organism (Sela et al, 2008, PNAS, 105(48): p. 18964-69).